1. Field of the Invention
This invention, in general, relates to a diameter-reducing member joint device, and more particularly to a diameter-reducing member joint device suitable to both the repair when the connection portion connected to a flange joint is broken and the mutual connection between the diameter-reducing pipes and for using a heat-shrinkable cylinder made of a shape memory alloy for the connection of at least a large-diameter portion.
The present invention also relates to a diameter-reducing member joint device suitable for use where the safety and reliability at a high level are required in such a joint device, for example, the pipeline joint devices in various nuclear power plants and chemical plants.
2. Description of the Prior Art
In general, the joint structure flange joints connects mutually pipes 1, 2, as shown in FIG. 10, by inserting the end portions of pipes 1a, 2a to be connected into flange joints 3, 4 composed of flanges 30, 40 and bosses 31, 41 projecting into one surface of the flanges 30, 40 from the direction of the bosses 31, 41, respectively, by adhering the top end portions of the bosses 31, 41 in the flange joints 3, 4 to the surface portions of the pipes 1a, 2a to be connected by welds 32, 42, respectively, and by tightening mutually the flanges 30, 40 with unshown bolts and nuts through O-ring 5.
In the joint structure shown in FIG. 10, the neighboring portions around the welds 32, 42 as the end bases of the flange joints 3, 4 and the pipes 1a, 2a are most fragile, and the pipes 1a, 2a in the neighborhood of the welds 32, 42 easily get cracks 2b or are broken. Repair when the pipe 2a gets the cracks 2b and the pipe 2a is broken are difficult because they take a very long time and require expert skill for example, for taking out a residual portion 2c of a pipe 2 within the flange joint 4 by removing the bead of the weld 42 and for needing the joint legs by welding to the pipe 2a shortened by separating the residual portion 2c.
In general, when the diameter-reducing pipes are connected to each other, the end portions of both pipes are also welded to a diameter-reducing pipe joint while the diameter-reducing pipe joint is placed between the end portions of the diameter-reducing pipe. However, such a connecting operation not only takes a long time, but also the repair operation at the breakage time of a welded portion between the diameter-reducing pipe joint and either of the pipes is very difficult as above-mentioned.
Furthermore, Japanese Patent Laid-open No. 50-93847 (U.S. patent application Ser. No. 404723 and No. 404724 on the date of Oct. 9, 1973, respectively) has disclosed a joint device for connecting a couple of pipes by pressing a metallic liner with its slightly larger diameter than that of the pipes to be connected against the pipe portion to be connected from an external direction due to the shape recovery force in its shrinkable direction resulting from heating a heat-shrinkable cylinder made of a shape memory alloy up to its shape recovery temperature to be shrunken, after the liner is inserted the heat-shrinkable cylinder and the mutual end portions of the pipes are inserted into the liner from both ends. However, any means for connecting the diameter-reducing members with each other by using the heat-shrinkable cylinder made of the shape memory alloy has not yet been proposed.